Processed on 2024-03-04 13:23:49 PST.


Disclaimer: Data presented here come from a variety of sources and do not represent official EPA measurements. Please visit AirNow for official measurements.


Cumulative exposure to smoke is an important public health metric. This report summarizes the cumulative number of days air quality monitors in Michigan spent in each AQI category during the the month of May.

The tables below include only permanent monitors measuring PM2.5 and show cumulative exposure under existing NAAQS (National Ambient Air Quality Standards) and under the 2024 revised standards for PM2.5.

In the tables and plots below, ‘Old’ designates cumulative days calculated using the 2023 PM2.5 NAAQS while ‘New’ is calculated using the 2024 revised PM2.5 NAAQS. The impact of the NAAQS revision is quite clear.

May in Michigan

May 2014 – 2 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 42 20 0 0 0 0 2
New 34 28 0 0 0 0 2

May 2015 – 2 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 39 23 0 0 0 0 2
New 26 36 0 0 0 0 2

May 2016 – 18 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 24 7 0 0 0 0 1
New 13 18 0 0 0 0 1

May 2017 – 1 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 28 3 0 0 0 0 1
New 19 12 0 0 0 0 1

May 2018 – 19 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 19 12 0 0 0 0 1
New 11 20 0 0 0 0 1

May 2019 – 2 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 26 5 0 0 0 0 1
New 13 18 0 0 0 0 1

May 2020 – 23 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 59 3 0 0 0 0 2
New 49 13 0 0 0 0 2

May 2021 – 20 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 480 125 0 0 0 0 35
New 362 243 0 0 0 0 35

May 2022 – 21 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 545 63 1 1 0 0 30
New 421 187 1 1 0 0 30

May 2023 – 21 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 447 197 0 0 0 0 28
New 324 320 0 0 0 0 28